This invention relates to a dual switch actuator mechanism for coordinated actuation of two high-current switches, each of which switch includes a switch operator mechanism for opening and closing the switch in response to operation of a switch operator shaft. Such mechanisms are shown in Erickson, et al. U.S. Pat. No. 4,103,133, and these mechanisms may be used on pairs of switches where it is desirable to close one switch while maintaining the other switch in its open position, called a "break-before-make" arrangement or to open one switch while maintaining the other switch closed, called a "make-before-break" arrangement.
In installations of dual load-break bolted pressure contact switches carrying loads of currents of the order of 400 to 6,000 amperes controlled by a dual switch operating mechanism which switches are operated in a "break-before-make" arrangement, a potentially hazardous situation may occur when the contacts of a switch weld in a partially closed position. Such a weldment is usually caused by the failure of the switch contacts to rapidly disengage when the switch is moved from a closed to an open condition. In such a situation, the Geneva follower plate of the switch that becomes welded may not rotate to its fully open position but may hang up in a position near but not completely at its fully open position. Even though this operator plate is not in its fully open position, the operator handle and its shaft may return to the neutral position leading an operator to erroneously believe that both switches are fully open. The operator handle may then be rotated from its neutral position to rotate its Geneva drive plate into engagement with the other Geneva follower plate to close the switch associated with this plate while at the same time the first switch is not completely open and is at least partially closed.